Caravan tow weights,

Have started doing research on caravans as looking at doing the round one next year,
We done three months in one about twelve years ago and loved it but got stuck in the rut again til now, anyway my tow vehicle is a 01 NM pajero petrol, before u say upgrade u'r tow , not happening, a few van sales persons have said I should. My answer if I upgrade can't get van as I have everything I need on mine.There is heaps of vans towed by pajero's, but I having trouble finding towball limit. Is it 180 or 250 . Is there a differance with the diesel compared to the petrol.,when I call on doctor google it seems to go to np models, so if someone can confirm towing weights for the NM be great,
Cheers pete